New model: Black holes, neutron stars drove Universe’s reionization

Composite X-ray, visible-light, and radio image of the X-ray binary Circinus X-1. This object is a neutron star in mutual orbit with an ordinary star. Such systems could have been responsible for the reionization of the cosmos in the era of the first stars and galaxies.

During the first billion years of the Universe's history, the gradual cooling from the Big Bang was reversed, and much of the gas was re-heated and ionized. This event, known as reionization, happened in the epoch where the first stars and galaxies formed. Largely due to the challenges of observing galaxies that far back in time, much is still mysterious about it. Most of our understanding of reionization comes from theoretical models.

One new model, proposed by Anastasia Fialkov, Rennan Barkana, and Eli Visbal, suggests that energetic X-rays could have heated the primoridal gas to the point that reionization happened relatively rapidly. That's in contrast with other hypotheses, which predict a more gradual reionization process. The X-rays in the new model were emitted by systems that include neutron stars or black holes. The nicest feature of the new proposal is that it predicts a unique pattern in light emission from the primordial gas, which could conceivably be measured by current radio telescopes.

Roughly 380,000 years after the Big Bang, the Universe became transparent. Before that time, the ordinary matter—mostly protons and electrons, with a smattering of helium nuclei—was a hot plasma mixed with photons. The transition to transparency occurred when the temperature of the plasma dropped low enough that electrons could join protons to make hydrogen, freeing the photons that we now observe as the cosmic microwave background.

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Some time after stable atoms formed, something reionized much of the gas in the Universe. Reionization happened somewhere between 150 million and one billion years after the Big Bang, the same era that saw the formation of the first stars and galaxies. However, this epoch is challenging to observe: astronomers have yet to see examples of the first generation of stars, and the great distance means that only a few of the earliest galaxies have been seen. Those were only visible thanks to magnification by gravitational lensing.

The culprits behind the reionization likely included energetic ultraviolet radiation from newborn stars in the first galaxies as well as X-ray light from the remnants of the first generation of stars to die. According to various models, high-mass stars formed in large numbers early in the Universe's history, but something that massive explodes in a supernova after a relatively short time. Many of the remains—neutron stars and black holes—would form binary systems with stars or other remnants, generating huge numbers of X-ray photons as they fed on stray matter.

Typical models predicted that these X-ray binaries would heat the primordial gas rapidly, creating bubbles of plasma surrounded by neutral material. However, the new model shows that the kind of high-energy X-ray photons would be very inefficient at transferring energy to the gas and would therefore heat it far more slowly. That means reionization occurred toward the end of the epoch rather than spreading out through the entire period. Additionally, reheating would be more uniform in this model, creating a smoother mix of plasma than the bubbles previous ideas had suggested.

The new predictions in this model have immediate observational consequences. For instance, the relatively late occurrence of reionization means the neutral gas was a lot cooler than in other models, leading to increased absorption that could be measured. While this signal would be very small—a few thousandths of a degree—several current and proposed radio telescopes could reach that level of sensitivity in the next few years. If this signature of neutral gas is measured, it would be a strong hint that X-ray binaries were responsible for a lot of reionization.

With the advent of observatories designed to study the epoch of reionization, it's more important than ever to get the theoretical foundation for that era right. After all, the best models help us guide and interpret observations. Without astronomical data, models were free to make assumptions that may or may not be justified. It's always better to have a variety of predictions available when the data starts coming in.

Where may I find a reasonably detailed timeline of the first few billion years of the universe? I watched the debate yesterday with a friend of mine and we got to talking about how much humanity has been able to infer about the formation of the elements and larger structure (solar systems, galaxies) of the universe. I'm hardly an expert on it so it would be nice to see a reasonably digestible overview with important moments highlighted.

Where may I find a reasonably detailed timeline of the first few billion years of the universe? I watched the debate yesterday with a friend of mine and we got to talking about how much humanity has been able to infer about the formation of the elements and larger structure (solar systems, galaxies) of the universe. I'm hardly an expert on it so it would be nice to see a reasonably digestible overview with important moments highlighted.

Where may I find a reasonably detailed timeline of the first few billion years of the universe? I watched the debate yesterday with a friend of mine and we got to talking about how much humanity has been able to infer about the formation of the elements and larger structure (solar systems, galaxies) of the universe. I'm hardly an expert on it so it would be nice to see a reasonably digestible overview with important moments highlighted.

this doesn't have the astronomical images i seem to recall seeing last time i watched BBT, but i find it interesting that someone would spend the time putting this together: http://haraldkraft.de/thebigbangtheory/

So, any chance that life emerged somewhere between the first transparency and the re-ionization? (I assume not much, given that the universe was presumably still very poor in minerals, but it's a wry fantasy that somewhere organisms had a furious debates over the need to colonize other planets, maybe even other solar systems as insurance against a global catastrophe snuffing them out, only to have the whole lot turn back into a plasma torch anyway...)

So, any chance that life emerged somewhere between the first transparency and the re-ionization? (I assume not much, given that the universe was presumably still very poor in minerals, but it's a wry fantasy that somewhere organisms had a furious debates over the need to colonize other planets, maybe even other solar systems as insurance against a global catastrophe snuffing them out, only to have the whole lot turn back into a plasma torch anyway...)

Absolutely no chance. Evidence indicates that the reionization was very thorough, which precludes any kind of complex chemistry.

One new model, [...] suggests that energetic X-rays could have heated the primoridal gas to the point that reionization happened relatively rapidly. That's in contrast with other hypotheses, which predict a more gradual reionization process. [...] , the new model shows that the kind of high-energy X-ray photons would be very inefficient at transferring energy to the gas and would therefore heat it far more slowly.

What am I missing? New model relatively rapidly, then new model far more slowly.

Quote:

On topic...the last sentence of this article is perfect.

Guess so if a model can at the same time predict two completely opposite results.

Every article like this makes me more eager for the James Webb telescope to be finished. (It's still a few years away.) Seeing in infrared beyond even the distance that Hubble sees will open a whole new part of the universe, and a new part of its history, to investigation. Spaces that are just black background in Hubble's Deep Field images could be teeming with anything from exotic young galaxies to weird and extremely informative blobs of gas.

I'm with Miles... the second paragraph talks about "One new model ...suggests that energetic X-rays could have heated the primoridal gas to the point that reionization happened relatively rapidly", then the six paragraph says "the new model ... would therefore heat it far more slowly".

two questions:1) what does the word "neutral" refer to in this context of "neutral gas"?2) "For instance, the relatively late occurrence of reionization means the neutral gas was a lot cooler than in other models, leading to increased absorption that could be measured" <- absorption of what in to what?

I'm with Miles... the second paragraph talks about "One new model ...suggests that energetic X-rays could have heated the primoridal gas to the point that reionization happened relatively rapidly", then the six paragraph says "the new model ... would therefore heat it far more slowly".

The old model had xrays being absorbed relatively rapidly creating a large number of small bubbles of ionized gas around xray sources that gradually expanded and merged together.

In the new model xrays aren't absorbed as rapidly, so instead of quickly heating a small volume around each individual source they traveled farther on average and gradually warmed a much larger volume. Because the heating zones from many sources would overlap heavily the gas ended up all getting hot enough to reionize at the end of the period.

It's not the best analogy but; but compare heating a bucket of water with unfiltered sunlight vs using a lens to concentrate the same amount of light on a small area. If you leave it out in unconcentrated light its entire volume will warm at roughly the same rate and all reach a given temperature at about the same time; this is the new re-ionization model. If you use a lens to concentrate all the incoming light into a small area in the bucket, the water there will quickly heat up and get much hotter than the water in the rest of the bucket although eventually all the water will get hot; this is the old model.

two questions:1) what does the word "neutral" refer to in this context of "neutral gas"?2) "For instance, the relatively late occurrence of reionization means the neutral gas was a lot cooler than in other models, leading to increased absorption that could be measured" <- absorption of what in to what?

1) non-ionized.

2) absorption of light. Plasma absorbs light much more rapidly and across a much wider spectrum than neutral gasses do.

1) I don't believe there is one universe as we know it. I believe they are in the same reality and just too far away from us for us to detect them. When was the last time you know of one of anything. Nothing is absolutely unique. Not really. Just variation of a theme.

2) So how long do they think the pre-big bang existed? Where did that matter that is the universe come from. It DID come from somewhere. It did have a beginning. Everything does. Personally I think that our big bang (which had no sound of course and which is just one of what I feel is billions out there) came from something that collapsed like a sun and then exploded back out. Like a dying sun but obviously much, much denser with a lot more mass. Other than it being just a lot, lot bigger, it really is no different from what I can understand.

3) And if this were the only big bang, which I obviously don't believe, what exactly do the scientists think is out beyond our universe. Do they _really_ think there is nothing else out there? I think that is just as stupid an idea as the idea that there were no planets around the other start in our universe. I believe there are as many universes as their are suns or maybe planets in our universe.

"However, this epoch is challenging to observe: astronomers have yet to see examples of the first generation of stars, and the great distance means that only a few of the earliest galaxies have been seen. Those were only visible thanks to magnification by gravitational lensing."

This made me think about something that i've been pondering lately, reading such articles - Is it possible that it's actually too late to see the first events in the universe? Since distance and time are kinda the same thing when observing space objects, what if ALL the light(or whatever other waves we can observe) emitted that long ago by the first events in the universe has already passed by our location relative to the event?

1) I don't believe there is one universe as we know it. I believe they are in the same reality and just too far away from us for us to detect them. When was the last time you know of one of anything. Nothing is absolutely unique. Not really. Just variation of a theme.

2) So how long do they think the pre-big bang existed? Where did that matter that is the universe come from. It DID come from somewhere. It did have a beginning. Everything does. Personally I think that our big bang (which had no sound of course and which is just one of what I feel is billions out there) came from something that collapsed like a sun and then exploded back out. Like a dying sun but obviously much, much denser with a lot more mass. Other than it being just a lot, lot bigger, it really is no different from what I can understand.

3) And if this were the only big bang, which I obviously don't believe, what exactly do the scientists think is out beyond our universe. Do they _really_ think there is nothing else out there? I think that is just as stupid an idea as the idea that there were no planets around the other start in our universe. I believe there are as many universes as their are suns or maybe planets in our universe.

You're describing a variation on the Pulse Theory, in which innumerable Big Bangs occur throughout a huge chaos. In general, these small-u universes will contract back under their own weight into Big Crunches which rebound into new Big Bangs, and so on. Entropy guarantees there will be differences after each pulse, but in principle there ought to be some information left behind about the previous universe in the next pulse.

Careful measurements of our Universe's expansion have also led to the conclusion that we are not destined to recoil back into a Big Crunch. What's left is the idea of multiple universes, which can be accommodated in a number of different cosmology theories.

1) I don't believe there is one universe as we know it. I believe they are in the same reality and just too far away from us for us to detect them. When was the last time you know of one of anything. Nothing is absolutely unique. Not really. Just variation of a theme.

2) So how long do they think the pre-big bang existed? Where did that matter that is the universe come from. It DID come from somewhere. It did have a beginning. Everything does. Personally I think that our big bang (which had no sound of course and which is just one of what I feel is billions out there) came from something that collapsed like a sun and then exploded back out. Like a dying sun but obviously much, much denser with a lot more mass. Other than it being just a lot, lot bigger, it really is no different from what I can understand.

3) And if this were the only big bang, which I obviously don't believe, what exactly do the scientists think is out beyond our universe. Do they _really_ think there is nothing else out there? I think that is just as stupid an idea as the idea that there were no planets around the other start in our universe. I believe there are as many universes as their are suns or maybe planets in our universe.

You're describing a variation on the Pulse Theory, in which innumerable Big Bangs occur throughout a huge chaos. In general, these small-u universes will contract back under their own weight into Big Crunches which rebound into new Big Bangs, and so on. Entropy guarantees there will be differences after each pulse, but in principle there ought to be some information left behind about the previous universe in the next pulse.

Careful measurements of our Universe's expansion have also led to the conclusion that we are not destined to recoil back into a Big Crunch. What's left is the idea of multiple universes, which can be accommodated in a number of different cosmology theories.

But would there be anything after a big crunch? The explosion of the "big bang" would be so great that it would vaporize, literally, everything in its wake. Nothing would be left.

1) I don't believe there is one universe as we know it. I believe they are in the same reality and just too far away from us for us to detect them. When was the last time you know of one of anything. Nothing is absolutely unique. Not really. Just variation of a theme.

2) So how long do they think the pre-big bang existed? Where did that matter that is the universe come from. It DID come from somewhere. It did have a beginning. Everything does. Personally I think that our big bang (which had no sound of course and which is just one of what I feel is billions out there) came from something that collapsed like a sun and then exploded back out. Like a dying sun but obviously much, much denser with a lot more mass. Other than it being just a lot, lot bigger, it really is no different from what I can understand.

3) And if this were the only big bang, which I obviously don't believe, what exactly do the scientists think is out beyond our universe. Do they _really_ think there is nothing else out there? I think that is just as stupid an idea as the idea that there were no planets around the other start in our universe. I believe there are as many universes as their are suns or maybe planets in our universe.

You're describing a variation on the Pulse Theory, in which innumerable Big Bangs occur throughout a huge chaos. In general, these small-u universes will contract back under their own weight into Big Crunches which rebound into new Big Bangs, and so on. Entropy guarantees there will be differences after each pulse, but in principle there ought to be some information left behind about the previous universe in the next pulse.

Careful measurements of our Universe's expansion have also led to the conclusion that we are not destined to recoil back into a Big Crunch. What's left is the idea of multiple universes, which can be accommodated in a number of different cosmology theories.

But would there be anything after a big crunch? The explosion of the "big bang" would be so great that it would vaporize, literally, everything in its wake. Nothing would be left.

that was my thought too. unless they're expecting to find a little note from God in/on a Higgs-Boson or something. (thus the horrible name some have given it)

1) I don't believe there is one universe as we know it. I believe they are in the same reality and just too far away from us for us to detect them. When was the last time you know of one of anything. Nothing is absolutely unique. Not really. Just variation of a theme.

2) So how long do they think the pre-big bang existed? Where did that matter that is the universe come from. It DID come from somewhere. It did have a beginning. Everything does. Personally I think that our big bang (which had no sound of course and which is just one of what I feel is billions out there) came from something that collapsed like a sun and then exploded back out. Like a dying sun but obviously much, much denser with a lot more mass. Other than it being just a lot, lot bigger, it really is no different from what I can understand.

3) And if this were the only big bang, which I obviously don't believe, what exactly do the scientists think is out beyond our universe. Do they _really_ think there is nothing else out there? I think that is just as stupid an idea as the idea that there were no planets around the other start in our universe. I believe there are as many universes as their are suns or maybe planets in our universe.

You're describing a variation on the Pulse Theory, in which innumerable Big Bangs occur throughout a huge chaos. In general, these small-u universes will contract back under their own weight into Big Crunches which rebound into new Big Bangs, and so on. Entropy guarantees there will be differences after each pulse, but in principle there ought to be some information left behind about the previous universe in the next pulse.

Careful measurements of our Universe's expansion have also led to the conclusion that we are not destined to recoil back into a Big Crunch. What's left is the idea of multiple universes, which can be accommodated in a number of different cosmology theories.

But would there be anything after a big crunch? The explosion of the "big bang" would be so great that it would vaporize, literally, everything in its wake. Nothing would be left.

Depending on your views on singularities, either all of the matter bounce off of each other at the Big Crunch / Big Bang event, or they all run through each other creating a "mirror" universe with each pulse. The difference is largely academic because the Pulse Theory was a proper theory with falsifiable assertions for feasible observations. Such observations were made and the assertions falsified.

1) I don't believe there is one universe as we know it. I believe they are in the same reality and just too far away from us for us to detect them. When was the last time you know of one of anything. Nothing is absolutely unique. Not really. Just variation of a theme.

2) So how long do they think the pre-big bang existed? Where did that matter that is the universe come from. It DID come from somewhere. It did have a beginning. Everything does. Personally I think that our big bang (which had no sound of course and which is just one of what I feel is billions out there) came from something that collapsed like a sun and then exploded back out. Like a dying sun but obviously much, much denser with a lot more mass. Other than it being just a lot, lot bigger, it really is no different from what I can understand.

3) And if this were the only big bang, which I obviously don't believe, what exactly do the scientists think is out beyond our universe. Do they _really_ think there is nothing else out there? I think that is just as stupid an idea as the idea that there were no planets around the other start in our universe. I believe there are as many universes as their are suns or maybe planets in our universe.

You're describing a variation on the Pulse Theory, in which innumerable Big Bangs occur throughout a huge chaos. In general, these small-u universes will contract back under their own weight into Big Crunches which rebound into new Big Bangs, and so on. Entropy guarantees there will be differences after each pulse, but in principle there ought to be some information left behind about the previous universe in the next pulse.

Careful measurements of our Universe's expansion have also led to the conclusion that we are not destined to recoil back into a Big Crunch. What's left is the idea of multiple universes, which can be accommodated in a number of different cosmology theories.

But would there be anything after a big crunch? The explosion of the "big bang" would be so great that it would vaporize, literally, everything in its wake. Nothing would be left.

Depending on your views on singularities, either all of the matter bounce off of each other at the Big Crunch / Big Bang event, or they all run through each other creating a "mirror" universe with each pulse. The difference is largely academic because the Pulse Theory was a proper theory with falsifiable assertions for feasible observations. Such observations were made and the assertions falsified.

If only everyone in science took defeat so gracefully.

"Depending on your views on singularities, either all of the matter bounce off of each other at the Big Crunch / Big Bang event, or they all run through each other creating a "mirror" universe with each pulse."

I don't buy that theory. I believe the "big crunch/big bang" is one universe with one reality with the force of the big bang vaporizing all matter that existed before the big crunch. I've seen math that says this isn't true but when they try to explain it their words are full of holes. Their math might be too but I'm no where near good enough at math to prove them wrong.

1) I don't believe there is one universe as we know it. I believe they are in the same reality and just too far away from us for us to detect them. When was the last time you know of one of anything. Nothing is absolutely unique. Not really. Just variation of a theme.

2) So how long do they think the pre-big bang existed? Where did that matter that is the universe come from. It DID come from somewhere. It did have a beginning. Everything does. Personally I think that our big bang (which had no sound of course and which is just one of what I feel is billions out there) came from something that collapsed like a sun and then exploded back out. Like a dying sun but obviously much, much denser with a lot more mass. Other than it being just a lot, lot bigger, it really is no different from what I can understand.

3) And if this were the only big bang, which I obviously don't believe, what exactly do the scientists think is out beyond our universe. Do they _really_ think there is nothing else out there? I think that is just as stupid an idea as the idea that there were no planets around the other start in our universe. I believe there are as many universes as their are suns or maybe planets in our universe.

You're describing a variation on the Pulse Theory, in which innumerable Big Bangs occur throughout a huge chaos. In general, these small-u universes will contract back under their own weight into Big Crunches which rebound into new Big Bangs, and so on. Entropy guarantees there will be differences after each pulse, but in principle there ought to be some information left behind about the previous universe in the next pulse.

Careful measurements of our Universe's expansion have also led to the conclusion that we are not destined to recoil back into a Big Crunch. What's left is the idea of multiple universes, which can be accommodated in a number of different cosmology theories.

But would there be anything after a big crunch? The explosion of the "big bang" would be so great that it would vaporize, literally, everything in its wake. Nothing would be left.

Depending on your views on singularities, either all of the matter bounce off of each other at the Big Crunch / Big Bang event, or they all run through each other creating a "mirror" universe with each pulse. The difference is largely academic because the Pulse Theory was a proper theory with falsifiable assertions for feasible observations. Such observations were made and the assertions falsified.

If only everyone in science took defeat so gracefully.

"Depending on your views on singularities, either all of the matter bounce off of each other at the Big Crunch / Big Bang event, or they all run through each other creating a "mirror" universe with each pulse."

I don't buy that theory. I believe the "big crunch/big bang" is one universe with one reality with the force of the big bang vaporizing all matter that existed before the big crunch. I've seen math that says this isn't true but when they try to explain it their words are full of holes. Their math might be too but I'm no where near good enough at math to prove them wrong.

Remember that in general relativity matter and energy are largely interchangeable. Even if everything is "vaporized" the distribution of energy in the explosion will still depend on the distribution of matter and energy that went into making it. Such fluctuations would be visible in the Cosmic Microwave Background.

To be clear, I don't buy the theory either since it's not consistent with observation.

I'm with Miles... the second paragraph talks about "One new model ...suggests that energetic X-rays could have heated the primoridal gas to the point that reionization happened relatively rapidly", then the six paragraph says "the new model ... would therefore heat it far more slowly".

The old model had xrays being absorbed relatively rapidly creating a large number of small bubbles of ionized gas around xray sources that gradually expanded and merged together.

In the new model xrays aren't absorbed as rapidly, so instead of quickly heating a small volume around each individual source they traveled farther on average and gradually warmed a much larger volume. Because the heating zones from many sources would overlap heavily the gas ended up all getting hot enough to reionize at the end of the period.

It's not the best analogy but; but compare heating a bucket of water with unfiltered sunlight vs using a lens to concentrate the same amount of light on a small area. If you leave it out in unconcentrated light its entire volume will warm at roughly the same rate and all reach a given temperature at about the same time; this is the new re-ionization model. If you use a lens to concentrate all the incoming light into a small area in the bucket, the water there will quickly heat up and get much hotter than the water in the rest of the bucket although eventually all the water will get hot; this is the old model.

Isn't the idea more like boiling than just heating. It gradually raised to a 'tipping point' of sort after which it rapidly ionized?

I think Mars went through a black hole. Really really hot,then supercooled,very quickly. Nobody knows really what the size of a black hole,or neutron star can be. They can be very very small,or very very large. You may be saying,well I'm seeing a black hole,and a neutron star. But you could also notice that not only is it seen, it 'actually exists'.